Cannot access other computers on LAN

[Lars Kruse]

Hello Julien,


Am Tue, 15 Jan 2019 09:30:23 +0100
schrieb Julien dupont <marcelvierzon at gmail.com>:

> In that case I see:
> IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq1, length 64
> IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq2, length 64
> IP 172.16.0.3 > 192.168.1.1: ICMP echo request, id2135, seq3, length 64
> 
> Packet goes through but no PONG back if I understand correctly. That's
> probably where it goes wrong.

Yes, the final response is missing.
But the above output also lacks the forwarded packets (into your
192.168.1.0/24 subnet).
Thus I could imagine, that at least one of the following items is true:
* "ip_forward" (/proc/sys/net/ipv4/ip_forward) is not enabled on 192.168.1.3
* firewall rules do not allow such packets to be forwarded (see the output of
  "iptables -L -vn") on 192.168.1.3


> On VPN_office 'tcdump -npi any icmp', on 192.168.1.100 'ping 172.16.0.3':
> 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq1, length 64
> 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq2, length 64
> 192.168.1.100 > 172.16.0.3: ICMP echo request, id 11452, seq3, length 64
> ...

This indicates, that your packets are leaving the host.
The next steps would be to check at which point they (or their response) get
lost.


Cheers,
Lars